Question: What is the member of a sports team of Iker Casillas that starts January 1st, 1991?
Paraphrase: Who became a member of the sports team Iker Casillas on January 1st, 1991?
SPARQL (Wikidata): SELECT ?obj WHERE { wd:Q11584 p:P54 ?s . ?s ps:P54 ?obj . ?s pq:P580 ?x filter(contains(YEAR(?x),'1999')) }